October 22nd, 2001. Takeru Shirogane, a boy who’d been living an ordinary life in peaceful Japan, suddenly wakes up in a world he doesn't recognize. In this world, humanity has fought a decades-long war against alien invaders called BETA, and is on the brink of defeat. Japan is now a militarized nation on the front lines of the war. Unsure of how he got here or what’s going on, Takeru gradually accepts his fate, and joins the United Nations army as a surface pilot in order to help save humanity. There, he fights alongside the people he loves. But even as mankind is in danger of extinction, the nations of the world refuse to work together. In the end, humanity is forced to abandon the Earth. Three years later, Takeru wakes up from a deep sleep, and finds himself back in his room he recognizes from his old world. Was it all a dream...? His hopes of arriving back home, however, only last for a moment before being mercilessly dashed. The calendar reads October 22nd, 2001. And outside his room is nothing but miles of rubble. He’s back where he began, on the first day he arrived in this parallel world! First, he travels worlds, and then, he leaps back in time. Still unsure of what's going on, he shakes off his disappointment and heads off into the waste, resolve in his heart. Now that he knows the future that waits this world, he can change the tragedy that befalls it. With his knowledge of mankind’s future defeat, and a strange sense of loss in his heart, he readies himself for the task before him. Will Takeru be able to lead mankind to victory?